This invention concerns a new device for the manufacture of non-woven fabrics having embossed or impressed designs, or even with perforations.
The invention also covers a new industrial product, namely the manufacture of the non-woven fabrics produced by the device described in the invention.
Perforated non-woven fabrics are well-known, especially for applications in the fields of medicine and hospital care, cleaning, filtering, etc.
For instance, there is the well-known French Patent No. 2,068,676 for transporting a sheet of wetted fibers on the porous material of a supporting conveyor belt. The fiber sheet is passed under a rotating perforated cylinder containing a hydraulic injector in the form of a fixed horizontal bar. The injector discharges a curtain of water under pressure, some of which passes through holes in the perforated cylinder. The water then penetrates the fiber sheeting in the appropriate places and is collected in a suction box below, located under the material of the conveyor belt, below the rotating cylinder.
This current device has several disadvantages. First of all, the lack of rigidity in the injector does not permit water to be injected under high pressure, nor is it possible to substantially reduce the thickness of the water curtain. In any case, it is difficult to control the thickness of the curtain with precision. Finally, since the curtain of water is directed perpendicularly onto the surface of the fiber sheet, there often occurs a problem with an overflow of water which is difficult to remove or pump out.
Furthermore, it has been calculated that the relatively weak kinetic energy of the curtain of water produced by most of the known machinery only permits treatment of lightweight fiber sheeting produced by the wetting method, i.e., fibers with limited bonded strength. Such machinery is often useless for fiber sheeting produced by dry methods.
The invention under review is aimed at eliminating these disadvantages, by producing an almost universally useful machine for the manufacture of non-woven fabric on which any kind of design can be imposed, whether it be in relief or impressed, or even perforated, and this would apply to fabrics produced by the wet or dry methods.